The idea in one line. "I like it" is taste. "It is appearing — here, since when, at this pace" is a signal. A moodboard built on taste describes you; a moodboard built on signals describes the market.
Why it matters. Brands don't pay for what you like. They pay for knowing what their customers will want next season. The moment you separate your aesthetic reaction from observable evidence, your moodboard stops being decoration and becomes an argument.
The core distinction. A taste statement needs no proof and cannot be wrong: "sheer layering feels fresh." A signal statement can be checked and therefore can be trusted: "sheer layering appeared in 4 of 9 Paris SS26 shows, and search interest for 'sheer dress' has grown for 5 consecutive months." Same observation, two different objects: one lives in your head, the other lives in the world.
Example. Two students pin the same photo of ballet flats. Student A writes: "so elegant, very 2000s." Student B writes: "third street-style appearance this month (Copenhagen, Seoul, Milan); resale listings up on Vestiaire; two mass-market drops announced." Same image — only B has produced knowledge.
Common mistake. Deleting taste. You don't. Taste selects where to look; signals decide what to claim. A great trend researcher runs both, and never lets one impersonate the other.
Check yourself. 1) Take any statement from your last moodboard. Can it be false? If it can't — it's taste. 2) Rewrite it so that a stranger could verify it without meeting you.
Sources. Rogers, Diffusion of Innovations — how new things spread. Palais Galliera / Europeana Fashion open collections — dating past appearances. Google Trends — observable search demand (interest is not sales).